Metric evaluation of the anterior nasal spine to estimate sex and population group in South African individuals.

INTRODUCTION: The anterior nasal spine is a pointed, midline projection of the maxilla. This bony structure dictates the overlying soft tissues providing the phenotypic features of the nose and upper lip and determines the differences in the mid-face morphology. Little data is available on the metric features of the Anterior nasal spine (ANS). This study aimed to perform metric evaluations of the ANS of white and black South African males and females to ascertain if morphological variations exist and if the differences are viable for the use in sex and population identification. MATERIALS AND METHODS: The sample included 100 CBCT images for each population and sex group. Linear and angular measurements of the ANS were recorded in both the sagittal and axial planes. RESULTS: Classification decision trees (pruned) were fitted to ascertain the relationship between population group, sex and the ANS measurements including and excluding age. For population group, all the ANS measurements were statistically significant for females but in males, all the ANS measurements were significant when performed individually. However, when fitted to the classification tree, Sagittal 2 did not show any statistical significance. When considering sex, only 2 of the ANS measurements (Sagittal 2 and Axial 1) were found to be significant. The results did not differ significantly when comparing the decision trees including and excluding age. CONCLUSIONS: White South African individuals presented with a longer ANS that produced a more acute angle whereas black South African individuals presented with a shorter ANS and a more obtuse angle. Additionally, males presented with a longer ANS compared to females. ANS measurements were found to be more relevant for population discernment than for sex.

Validation of Roberts' method using root canal width patterns as a mandibular maturity marker in determining the 18-year threshold.

The South African Bill of Rights and the Children's Act define a 'child' as a person under the age of 18 years. The age of 18 years is therefore significant for legal purposes in South Africa. The third molar is an important indicator in determining the 18-year threshold. Human biological growth markers are accepted indicators of a subject attaining the age of 18 years. A recent study by Roberts et al. suggested that the relative width of the distal root canals (RCW) of the lower left permanent molars (Fédération Dentaire Internationale notation 36, 37 and 38) as visualised on dental panoramic radiographs can be used as such a growth marker. This study aimed to validate this human biological growth marker in both black and white populations living in South Africa according to Roberts' method. The findings of this validation study were in agreement with this method which showed that individuals with Demirjian stage H left molars and category RCW-C were indeed over the 18-year threshold. Important aspects regarding the rationality and application of Roberts' method are discussed. The authors conclude that this method should not be used in isolation but as an adjunct with other age estimation methods.

Structural features of alternative lignin monomers associated with improved digestibility of artificially lignified maize cell walls.

Plant biologists are seeking new approaches for modifying lignin to improve the digestion and utilization of structural polysaccharides in crop cultivars for the production of biofuels, biochemicals, and livestock. To identify promising targets for lignin bioengineering, we artificially lignified maize (Zea mays L.) cell walls with normal monolignols plus 21 structurally diverse alternative monomers to assess their suitability for lignification and for improving fiber digestibility. Lignin formation and structure were assessed by mass balance, Klason lignin, acetyl bromide lignin, gel-state 2D-NMR and thioacidolysis procedures, and digestibility was evaluated with rumen microflora and from glucose production by fungal enzymes following mild acid or base pretreatments. Highly acidic or hydrophilic monomers proved unsuitable for lignin modification because they severely depressed cell wall lignification. By contrast, monomers designed to moderately alter hydrophobicity or introduce cleavable acetal, amide, or ester functionalities into the polymer often readily formed lignin, but most failed to improve digestibility, even after chemical pretreatment. Fortunately, several types of phenylpropanoid derivatives containing multiple ester-linked catechol or pyrogallol units were identified as desirable genetic engineering targets because they readily formed wall-bound polymers and improved digestibility, presumably by blocking cross-linking of lignin to structural polysaccharides and promoting lignin fragmentation during mild acidic and especially alkaline pretreatment.

Prevalence of oral and oropharyngeal human papillomavirus in a sample of South African men: a pilot study.

BACKGROUND: Human papillomavirus (HPV) infection is well known to be associated with head and neck cancers (HNCs). HPV-associated HNCs are related to sexual behaviour, particularly the lifetime number of oral sex partners, but the epidemiology of oral and oropharyngeal HPV in South African men has not yet been studied. OBJECTIVES: To determine the oral and oropharyngeal HPV strain prevalence and associated factors in a selected male population in Pretoria, South Africa (SA). METHODS: Male factory workers were recruited. Oral rinse and gargle samples were tested for 37 HPV types using the Linear Array HPV Genotyping Test (Roche Molecular Systems). A questionnaire was used to obtain information regarding age, medical conditions, substance and alcohol use and sexual behaviour. HIV testing was optional. RESULTS: The HPV prevalence was 5.6% among men (N=125) aged 17 - 64 years. High-risk HPV (hrHPV) types 16 and 68 were found in two men. Oral sex seemed to be an uncommon practice in the majority of respondents, but the two respondents with hrHPV did practise oral sex. There was a statistically significant association between HPV infection and an increased number of sexual partners (p=0.027), but not between HPV and substance use, HIV status or clinical mucosal pathology. CONCLUSION: The prevalence of oral and oropharyngeal HPV was lower than reported in other countries. An association between oral HPV and having multiple sexual partners was found. A larger nationwide study would give a more representative view of the burden of oral and oropharyngeal HPV infection in SA.

Hydroxycinnamate conjugates as potential monolignol replacements: in vitro lignification and cell wall studies with rosmarinic acid.

The plasticity of lignin biosynthesis should permit the inclusion of new compatible phenolic monomers, such as rosmarinic acid (RA) and analogous catechol derivatives, into cell-wall lignins that are consequently less recalcitrant to biomass processing. In vitro lignin polymerization experiments revealed that RA readily underwent peroxidase-catalyzed copolymerization with monolignols and lignin oligomers to form polymers with new benzodioxane inter-unit linkages. Incorporation of RA permitted extensive depolymerization of synthetic lignins by mild alkaline hydrolysis, presumably by cleavage of ester intra-unit linkages within RA. Copolymerization of RA with monolignols into maize cell walls by in situ peroxidases significantly enhanced alkaline lignin extractability and promoted subsequent cell wall saccharification by fungal enzymes. Incorporating RA also improved cell wall saccharification by fungal enzymes and by rumen microflora even without alkaline pretreatments, possibly by modulating lignin hydrophobicity and/or limiting cell wall cross-linking. Consequently, we anticipate that bioengineering approaches for partial monolignol substitution with RA and analogous plant hydroxycinnamates would permit more efficient utilization of plant fiber for biofuels or livestock production.

Fluorescence-tagged monolignols: synthesis, and application to studying in vitro lignification.

Fluorescence-tagged coniferyl alcohols, coniferyl alcohol γ-coupled by ethylenediamine spacers to dimethylaminocoumarin or nitrobenzofuran fluorophores, were tested as photoprobes to study the oxidase-mediated polymerization of monolignols. The fluorescent coniferyl alcohol derivatives readily underwent peroxidase-catalyzed in vitro copolymerization with coniferyl alcohol to yield fluorescent dehydrogenation polymers, the backbone polymers of which were structurally indistinguishable from polymers formed solely from coniferyl alcohol. To illustrate the use of the photoprobes, we successfully monitored in real time the complexation of coniferyl alcohol with horseradish apoperoxidase by Förster resonance energy transfer (FRET) using the protein-tryptophan near the active site and a dimethylaminocoumarin moiety as donor and acceptor fluorophores. Furthermore, mixtures of fluorescence-tagged and normal coniferyl alcohols readily diffused into isolated maize cell walls and reacted with wall-bound peroxidases to form in muro artificial lignins that could be visualized by fluorescence microscopy. Thus we anticipate that fluorescence-tagged monolignols will be useful for in vitro and in vivo studies of cell wall lignification.